Stroboscopic apparatus



Aug. 24 ,-1926. 1,597,586 A. J. H. ELVERSON STROBOSCOPIC APPARATUS Filed August 11, 1922 m'ww/M, JHTEZbenson Patented Aug. 24%, 1926.

U IT E S T T E S PATENT OFFICE. i

ARTHUR J OHN HAWES ELVEIRSON,

OF WIMIBLEDON, ENGLAND, ASSIGNOR TO HER- BERT KENNEDY & COMPANY LIMITED, OF

WESTMINSTER, LONDON, ENGLAND.

STROBOSCQPIC APPARATUS.

Application filed. August 11, 1922, Serial No. 581,252, and in Great Britain December 8, 1921.

This invention relates to stroboscopic apparatus for use in studying the movement of bodies moving at relatively high speeds in a' periodic manner.

An object of the invention is to provide improved apparatus of the kind having flashing means driven synchronously with the moving body (hereinafter referred to as the mechanism) and having also flashing means driven at a speed differing slightly from that of the mechanism so that the mechanism may appear to be still or to traverse its path at a relatively low speed.

A further object is to provide improved means for transmitting the flashes electrically in which the flashing means is timed by contacts or cams formed on the sides of discs or gear wheels driven from the mechanism.

A further object is to provide improved electric connections whereby a microphone or transmitter is arranged in one circuit of a transformer containing a battery or other source of electric power and the receiver is coupled up with the stroboscopic switch gear in the other circuit, thus eliminating sound in the receiver due to make and break of the electric contacts.

\Vith the above and other objects which will hereinafter appear, the invention consists in the combinations and arrangements of parts set out in the following description and delimited by the claims.

In the usual form of the improved instrument the driving shaftiof the mechanism to be studied is connected by a chuck or the like carried by a central shaft upon which is mounted a 99-tooth wheel. meshes on opposite sides with a synchronous flashing wheel carrying 99 teeth and a differential flashing wheel carrying 100 teeth so that the mechanism viewed through the synchronous flashing means appears to be stationary and through the difierential flashing.means appears to perform its cyclic movement of of its true speed.

In some cases of bodies moving at great speed a reduction of e is desired; this ma be obtained by driving the differential flashing disc through a compound ar train with successive wheels having 2 40, 3? and 25 teeth.

Alternatively, by the pound. gears two or more selective use of comdiflerential flash- T his wheel ing means may be obtainedto give different speed reductions.

It will be understood that in order to give more than one flash per cycle of the mecha nism in order to enable secondary vibrations and the like to be studied the flashing discs may carry one, two, four or other convenient number of evenly spaced cams at different radial distances the co-operating contact member being correspondingly radially adjustable.

In the accompanying drawings which illustrate a preferred embodiment of the invention, v

Fig. 1 represents an elevation of the apparatus, partly in section.

Fig. 2 represents a sectional plan of the apparatus shown in Fig. 1.

Fig. 3 represents in conventional form the improved electric circuit for microphone use.

Figure 4: diagrammatically shows a modified arrangement for varying the flashes.

Referring first to Figs. 1 and 2, a shaft coupled to the shaft of the mechanism to be studied is carried by a chuck A carried by the spindle of a gear wheel B mounted centrally in a circular casing G; this wheel B has ninety-nine teeth out upon it and engages on opposite sides with two flashing wheels 8 and D, the former of which has ninety-nine teeth and is hereinafter referred to as the synchronous flashing wheel and the latter of which has one-hundred teeth and is hereinafter referred to as the differential flashing wheel.

Mounted upon the flashing wheels are four cams 0, two cams b and one earn at having inclined upper faces and arranged at different radial distances the back or steep edges of the faces being on the same radial line in each group and in the case of the cams b and 0 being spaced respectively 180 and 90 degrees apart. A contact-member d is provided for each flashin wheel and is mounted in a guide in a radial y movable slide 6. Each slide is capable of three radial positions determined by the engagement of a spring detent pin f with a hole 9 in the case. I

lhe cams and holes 9 are so proportioned that in the position shown the contact member d will be enga ed by both cams b so that the contact mem er will be reciprocated twice for each revolution of the flashing wheel; that if the slide 6 be'moved to its position towards the center of the instrument, the contact member will engage the cam a only so that it will be reciprocated once for each revolution'of the flashing wheel; and that if the slide e be moved to its position away from the center of the instrument, the contact member will engage the four cams 0 and thus will be reciprocated four times for each revolution of the flashing wheel.

The contact member d moves against the action of a spring it into engagement with a contact strip 21 carried upon a disk E of insulating material thus completing an electric circuit between terminals T, T? through the cams at timed periods, the breaking of said circuit due to the contact member passing over the steep edge of the cam causing the light flash to be given.

. T and T necessary primary and A lamp L suitable for the purpose of giving flashes is placed in a circuit R of a battery U. A casing M containinglthe secondary coils, high and low tension condensers and spark gap, is shown in connection with Figure 1 having wires R connected with the binding posts Since the elements of the easing as recited form no part of the invention a conventional form of easing only is shown to include such elements.

The disk E is capable of two diametrically opposed positions, determined by the engagement of a pin 7' with the ends of a recess k formed upon the boss F of the casing to which the disk is secured by a set screw Z acting through a spring washer m.

In the position shown contact is made through the cams a, b and 0 on the differential flashing wheel so that flashes will occur which will make the mechanism under observation appear to perform its cyclic movement at one hundredth of its speed if the disk be turned through one hundred and ei hty de ees the synchronous flashing wheel g Will f il anism will appear stationary.

The instrument is held in a stand n which is conveniently provided with a ring clip 19 provided with clamping means 9 for engagement with a recessed boss F and the phase of the movement of the mechanism at which it appears to be stationary is adjusted by turning the instrument relatively to the clip or like holding means. This phase is indicated by a circularly divided scale G which co-operates with a fixed index pointer 0 or the like.

Friction pads H are preferably carried by the casing so Wheels in order rors.

In a modified arrangement of the ap to minimize backlash erction and the mechas to bear on the flashing paratus a number of axially movable contact members 2, 3 and 4, capable of being switched into circuit in order to give flashes at fractional periods, may be employed on either wheel S or D in co-operation with a single contact or cam 1 mounted on the wheel; in such an arrangement no means need be provided for radial adjustment of the contact members.

Referring to- Fig. 3 of the drawings a microphone transmitter T is connected in circuit with a battery and one winding of an induction coil or transformer I the return wire being conveniently earthed. The receiver R is placed in circuit with the other winding of the transformer and with the terminals T, T of the instrument D.

The microphone is conveniently mounted in a sound collector resembling a stethoscope and transmitsits induced currents through the transformer to the receiver which is switched into and out of circuit by the stroboscopic switch gear.

By placing the microphone on a portion of the mechanism where knocks or like audible irregularities occur and varying the phase at which the synchonous switch gear functions until a sound is audible in the receiver, the phase of the knock can be determined and by listening with the differential switch gear in circuit the existence and frequency of knocks vcan first be ascertained.

I claim:

1. In stroboscopie apparatus for studying the movements of mechanism moving at relatively high speed, the combination of a plurality of revolving driven members, means to drive one of said members at a speed synchronous with that of said mechanism and another of said members at a nearly synchronous s ed, a plurality of electrical contact mem birs for each driven member capable oftbeing each actuated once per revolution of said driven member, flashing means, and selective means movable to causea variable number of said contact members to operate said flashing means.

2. In stroboscopic apparatus for studying the movements of mechanism moving at relatively highspeed, the combination of meansdrivcn by said mechanism for influencing an electrical circuit to produce a periodical flash, and means to vary the number of flashes produced per revolution of said driven means, the said means comprising sets of equally spaced units, so that any of the different predetermined numbers of flashes is automaticall produced with equal intervals between individual flashes.

3. In a stroboscopic apparatus for studying the movements of. mechanism moving at a relatively high speed, a flashing means,

\ means for varying the number of flashes per revolution of the driven member of the mov- 111g mechanism and comprising a number of sets of contact members, the individual sets having different numbers of contact memstudied, one gear wheel driven synchronously by said main gear wheel and provided with a device capable of operating flashing means and a second gear wheel driven at a slightly asynchronous speed by 5 saidmain gear wheel and provided with a device capable of operating flashing means.-

5. In stroboscoplc apparatus, means to produce synchronous or differential flashes at will, comprising a main gear wheel driven synchronously with the mechanism to be studied, one gear wheel driven synchronously by said main gear wheel and provided with a device capable of ,operatin flashing means and a second gear whee driven at a'slightly asynchronous speed by said-main gear wheel and provided with a device capable of operating flashing means together with means whereby either of the devices mentioned may be made operative and the other inoperative to produce flashes. 6. A stroboscopic a paratus for studying the movements of meta anism moving at relatively high speeds com rising a gear wheeldriven at a speed corre ated to that of the mechanism to be studied, a second gear wheel driven by said first gear wheel and capable of transmitting flashes, and a mounting nously by sai bearing said wheels and capable of rotation about the axiso'f said first named wheel.

7, A stroboscopic, apparatus for studying the movements of mechanisms moving at relatively high speeds in which a main gear wheel driven synchronously with the mecha-' nism engages a gear wheel capable of transmitting synchronous flashes, the second wheel being capable of planetary motion about'the main gear wheel to adjust the phase of the mechanism at which flashes occur.

8. In stroboscopic apparatus, means to produce synchronous or difierential flashes at will, comprising a main gear wheel driven synchronously with the" mechanism to be studied, one (gear wheel driven synchromain gear wheel and provided with a device capable ofoperating flashing means. and a second gear wheeldriven at a slightly asynchronous speed by said main ear wheel and provided with a device capa 1e of operating flashing means and friction pads operating upon each of said gear wheels driven by said main gear whee 9. In stroboscopic apparatus for studying the movements of mechanism moving at rela-' tively high speed, the combination of electric-contact-makin means driven from said mechanism a circuit containing said contactmaking means, .a microphone receiver in said.

circuit, one winding of a transformer in said circuit, a second wlnding of said transformer, a second circuit containing said second winding, a transmitter in said second circuit and a source of electric supply to said second circuit.

In testimony whereof I afiix my signature.

Aiu'uun JOHN HAWES rivmsoa 

